LEAN FIT & FAST!
The New Rules of Fuel
an international team of sports scientists led by Vincent Onywera of Kenyatta University, Kenya, spent a week monitoring everything a group of 10 top Kenyan male distance runners ate and drank. To the surprise of no one, the researchers discovered that the diet of these athletes was quite good overall. They ate plenty of vegetables and healthy starches (mainly cabbage, beans, cornmeal and potatoes), a limited amount of meat (mostly beef) and almost nothing processed.
There was, however, one notable exception to the wholesomeness of the regular menu of these runners: a whopping 20 per cent of their calories came from refined sugar. No, they weren’t snacking on sweets or swilling soft drinks all day. They just drank a lot of tea, which Kenyans like to take loaded with milk and table sugar. Still, 20 per cent is a lot – far more than the 12 per cent contribution that refined sugars make to the diet of the average adult in the UK. This is, of course, considered to be too high in sugar.
In the 13 years since this study was conducted, Kenya’s elite runners have continued to fuel their bodies with super-sweet tea, something I saw for myself when I visited the country in 2015 to research my new book, Theendurance Diet (Da Capo Lifelong). These Kenyan elites, have, of course, continued to perform exceptionally well in competition. Meanwhile, growing numbers of recreational runners in other parts of the world have striven to eliminate sugar from their diet and even to avoid using sugar-containing products during training and competition. These efforts are based largely on a recent wave of negative news reporting on sugar, which has been labelled a ‘drug’ a ‘toxin’ and ‘poison’ But if the best runners on earth are among the heaviest sugar consumers, can it really be so bad?
Not according to the experts. ‘Sugar has become the scapegoat du jour in our public discourse about nutrition,’ says Dr David Katz, President of the American College of Lifestyle Medicine. ‘This is fine on one level, because many of us eat too much of it and would benefit from eating less. On another level, however, this kind of absolutist, either/or thinking about nutrition also carries negative consequences.’
For runners, the consequences of an excessive fear of sugar may include fitness stagnation resulting from inadequate carbohydrate intake (sugar is a carb) and also poor race performance resulting from failure to take advantage of the performanceenhancing effects of sugar intake during competition.
The truth about sugar is that it has pros and cons. On the plus side, it makes food taste good and it provides quick energy during intense activity. On the minus side, overconsumption of sugar has been proven to lead directly or indirectly to weight gain, insulin resistance and various cardiovascular disease risk factors. Enjoying the benefits of sugar while avoiding its negatives requires a balanced and smart approach to sugar consumption. To find this balance, follow these six science-based sugar rules.
DON’T WORRY ABOUT NATURAL SUGARS
There are two basic categories of sugar: natural and refined. Natural sugars are, as the name suggests, naturally present in foods. Examples are lactose in milk and fructose in fruit. Refined sugars are extracted from natural foods and then added to other foods and drinks to make them sweeter. Examples are high-fructose corn syrup, which is used in soft drinks, and sucrose (or table sugar), an ingredient in many desserts.
Some nutrition experts (and would-be experts) caution people to avoid natural and refined sugar sources alike, on the grounds that ‘sugar is sugar’. Consider this quote from a popular fitness website: ‘Some studies suggest fructose, the main type of sugar found in fruit, can even be more harmful than other sugars (namely, glucose). Fructose has even been linked to increased belly fat, slowed metabolism and overall weight gain.’
It’s true that fructose is the main type of sugar found in fruit. It’s also true that fructose appears to be more harmful than other types of sugar – but only when it’s not contained in fruit. Whole fruit itself, however, is one of the healthiest things you can eat. A recent study at Harvard University, US, found that a high intake of fruit was more effective than a high intake of vegetables in preventing weight gain.
DO EAT REFINED SUGAR IN MODERATION
Anti-sugar activists such as Gary Taubes, author of Thecaseagainst Sugar (Portobello Books), have popularised the idea that refined sugar, especially fructose, is uniquely potent as a contributor to weight gain and metabolic diseases. The biochemistry underlying this argument is complex, but the basic idea is that 100 calories of sugar are more fattening that 100 calories of anything else you might eat.
The problem with this idea is that most of the scientists actually doing the research it’s supposedly based on (Taubes is a science writer, not a scientist) don’t endorse it. ‘If you don’t overeat sugar, it doesn’t have any special effect compared to any other form of carbohydrate,’ says Stephan Guyenet, a neurobiologist and author of Thehungrybrain (Flatiron Books).
Guyenet points to the work of John Sievenpiper, a nutrition scientist at the University of Toronto and one of the world’s leading experts on the health effects of sugar consumption. Sievenpiper’s research has yielded compelling evidence that refined
Many foods besides sweets also contain added sugars